power: supply: smb347-charger: IRQSTAT_D is volatile

Fix failure when USB cable is connected:
smb347 2-006a: reading IRQSTAT_D failed

Fixes: 1502cfe1 ("smb347-charger: Fix battery status reporting logic for charger faults")
Tested-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/smb347-charger.c

@@ -1138,6 +1138,7 @@ static bool smb347_volatile_reg(struct device *dev, unsigned int reg)
 	switch (reg) {
 	case IRQSTAT_A:
 	case IRQSTAT_C:
+	case IRQSTAT_D:
 	case IRQSTAT_E:
 	case IRQSTAT_F:
 	case STAT_A: